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<body class="article toc2 toc-left">
<div id="header">
<h1>Glue</h1>
<div class="details">
<span id="author" class="author">Vinay Kumar</span><br>
<span id="revnumber">version 2.4.5</span>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#truewhat-is-glue">What is Glue?</a></li>
<li><a href="#trueconfiguration-layer">Configuration Layer</a>
<ul class="sectlevel2">
<li><a href="#truemultiple-configuration-layers">Multiple Configuration Layers</a></li>
</ul>
</li>
<li><a href="#truesupported-property-type">Supported Property Type</a></li>
<li><a href="#trueproperties-based-configuration-in-detail">Properties based configuration in detail</a>
<ul class="sectlevel2">
<li><a href="#truebasic-properties-file-configuration">Basic Properties File Configuration</a></li>
</ul>
</li>
<li><a href="#trueconfiguration-layer-in-detail">Configuration layer in detail</a>
<ul class="sectlevel2">
<li><a href="#trueoverride-property-value">Override Property Value</a></li>
</ul>
</li>
<li><a href="#truefactory-based-creation-of-component">Factory based creation of Component</a>
<ul class="sectlevel2">
<li><a href="#truemethodinstancefactory">MethodInstanceFactory</a></li>
<li><a href="#trueparameterconstructorinstancefactory">ParameterConstructorInstanceFactory</a></li>
</ul>
</li>
<li><a href="#trueadvance">Advance</a>
<ul class="sectlevel2">
<li><a href="#trueconfiguration-using-glue-config-file">Configuration using glue.config file</a></li>
<li><a href="#trueimprove-config-loading-performance">Improve config loading performance</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p>Proven and opinionated programming, and configuration model for Java
and Vertx based applications. Inspired from ATG Nucleus, provides
powerful layer base configuration management using simple properties file.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="truewhat-is-glue"><a class="anchor" href="#truewhat-is-glue"></a>What is Glue?</h2>
<div class="sectionbody">
<div class="paragraph">
<p>You will use Glue for same reason you will use Spring (dependency injection)
in your application. But, in case of Glue, we have implemented few concepts
to make your life much easier from development point of view.</p>
</div>
<div class="imageblock">
<div class="content">
<img src="./images/diag1.png" alt="Simple Hello World">
</div>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p><strong>HelloWorld class</strong> :
We want to set <code>mHelloWorld</code> field to <strong>This is hello world example</strong>.
Normally, this is done by creating new instance of <code>HelloWorld</code> class and then calling
<code>setHelloWorld</code> method to set <code>mHelloWorld</code> field. With <strong>Glue</strong>, this is done automatically.
You just need to define a property file with values.</p>
</li>
<li>
<p><strong>Component Path:/in/erail/example/HelloWorldComponent</strong>
<strong>(File Name:HelloWorldComponent.properties)</strong> :
This file is used to create instance of <code>HelloWorld</code> class and set property values as
defined in property file.</p>
</li>
<li>
<p>To get instance of <strong>HelloWorld</strong> class, you just need to call <code>HelloWorld</code>
<code>inst = Glue.instance().&lt;HelloWorld&gt;resolve("/in/erail/example/HelloWorldComponent")</code></p>
</li>
</ol>
</div>
</div>
</div>
<div class="sect1">
<h2 id="trueconfiguration-layer"><a class="anchor" href="#trueconfiguration-layer"></a>Configuration Layer</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Configuration layer is root directory under which all configurations exists. For example, you
want to create instance of <code>HelloWorld</code> class. Then, you will have to do below steps.</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Create configuration layer on your file system. For example <code>/home/glue/layer1</code>. This
folder will become root folder for all configurations.</p>
</li>
<li>
<p>Then create <code>HelloWorldComponent.properties</code> file at
<code>/home/glue/layer1/in/erail/example/HelloWorldComponent.properties</code>.</p>
</li>
<li>
<p>When you run your code, you will pass configuration layer to glue as java parameters.
<code>java -Dglue.layers=/home/glue/layer1</code>. Now whenever you want to get instance of <code>HelloWorld</code>,
<code>HelloWorld inst = Glue.instance().&lt;HelloWorld&gt;resolve("/in/erail/example/HelloWorldComponent")</code>.
<code>HelloWorld</code> instance will be configured based on
<code>/home/glue/layer1/in/erail/example/HelloWorldComponent.properties</code> file.</p>
</li>
</ol>
</div>
<div class="sect2">
<h3 id="truemultiple-configuration-layers"><a class="anchor" href="#truemultiple-configuration-layers"></a>Multiple Configuration Layers</h3>
<div class="paragraph">
<p>You can define multiple configuration layers. Properties file defined at same location inside
all layers are merged. And last overridden value is taken as value of property.
for example:</p>
</div>
<div class="listingblock">
<div class="title">Layer 1 (/testdata/layer1/)</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/MergedComponent
$class=in.erail.glue.component.PropertiesComponent
$scope=LOCAL
propString=TestString</code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">Layer 2 (/testdata/layer2/)</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/MergedComponent
$scope=GLOBAL
propString=TestString2</code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">Final merged component configuration:</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/MergedComponent
propString=TestString2
$scope=GLOBAL</code></pre>
</div>
</div>
<div class="paragraph">
<p>As you can see above, second layer has overridden propString property.</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="truesupported-property-type"><a class="anchor" href="#truesupported-property-type"></a>Supported Property Type</h2>
<div class="sectionbody">
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Java Type</th>
<th class="tableblock halign-left valign-top">Example</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">String</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propString=TestString</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Array[String]</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propArray=a,b,c</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Array[Component]</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propArray=/abc/comp1,/abc/comp2</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">List&lt;String&gt;</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propList=a,b,c</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Map&lt;String,String&gt;</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propMap=a=b,c=d,e=f</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Boolean and boolean</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propBoolean=true</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Enum</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propEnum=TWO</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Set&lt;String&gt;</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propSet=a,b,b,c</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Integer and Int</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propInteger=2</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Long and long</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propLong=2</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">File</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propFile=testconfig.json</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">JsonObject (Vertx)</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propFile=testconfig.json</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">ServiceMap</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Map of components</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Logging</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Logging component</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Reference to another component</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Null</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Null value</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Pattern</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">String will be compiled into Pattern</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Timer (Dropwizard Metric)</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">a timer will be created based on name given</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Counter (Dropwizard Metric)</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">a counter will be created based on name given</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Meter (Dropwizard Metric)</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">a meter will be created based on name given</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Histogram (Dropwizard Metric)</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">a hitogram will be created based on name given</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">Class</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">propClass=java.lang.String</p></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="sect1">
<h2 id="trueproperties-based-configuration-in-detail"><a class="anchor" href="#trueproperties-based-configuration-in-detail"></a>Properties based configuration in detail</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">Example Property File</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/PropertiesComponent
$class=in.erail.glue.component.PropertiesComponent
$scope=LOCAL
propString=TestString
propArray=a,b,\
    c
propList=a,b,\
    c
propMap=a=b,c=d,\
    e=f
propComponent=/in/erail/glue/test/component/GlobalObjectByDefault
propBoolean=true
propEnum=TWO
propSet=a,b,b,c
propBoolean2=true
propServiceMap=\
    a=/in/erail/glue/test/component/GlobalObjectByDefault,\
    b=/in/erail/glue/test/component/GlobalObjectByDefault,\
    c=/in/erail/glue/test/component/GlobalObjectByDefault
propInt=2
propInteger=2
propFile=testconfig.json
propLong=2
propLong2=2
propLogger=true
propNullString=
propNullServiceMap=
propNullComponent=</code></pre>
</div>
</div>
<div class="paragraph">
<p>Above is test property file <code>PropertiesComponent.properties</code> to create component
<strong>PropertiesComponent</strong>. Physically, it is present in folder <code>/in/erail/glue/test/component/</code>.
Folder structure itself is present in another folder called <strong>configuration layer</strong> folder.
We can provide multiple configuration layers to Glue. Physical location of
PropertiesComponent.properties file under configuration layer becomes actual mounting
point of component. In this case, PropertiesComponent is mounted at
<code>/in/erail/glue/test/component/</code>. To get instance of PropertiesComponent, we use
<code>/in/erail/glue/test/component/PropertiesComponent</code> path.</p>
</div>
<div class="sect2">
<h3 id="truebasic-properties-file-configuration"><a class="anchor" href="#truebasic-properties-file-configuration"></a>Basic Properties File Configuration</h3>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 25%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Property Name</th>
<th class="tableblock halign-left valign-top">Required</th>
<th class="tableblock halign-left valign-top">Default</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">$class</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Yes</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">N/A</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Instance of this class will be created whenever instance of this component is created.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">$scope</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">No</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">GLOBAL</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Default scope of component is "GLOBAL". Means, Whenever instance of this component
is required, same instance of component is returned. This is same as Singleton Pattern.
If new instance is required on each component creation call then "LOCAL" scope can be
defined. This will ensure, Glue will return new instance each time.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">$basedOn</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">No</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">N/A</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">One component can copy all property values of another component. And override only
required properties</p></td>
</tr>
</tbody>
</table>
<div class="listingblock">
<div class="title">$basedOn Example</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/BasedOnPropertiesComponent
$basedOn=/in/erail/glue/test/component/PropertiesComponent
propString=TestString2</code></pre>
</div>
</div>
<div class="paragraph">
<p>In above example, all properties of this component will have value as set in
<code>/in/erail/glue/test/component/PropertiesComponent</code> component. And in this component
<code>propString</code> will be overridden with value <code>TestString2</code></p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="trueconfiguration-layer-in-detail"><a class="anchor" href="#trueconfiguration-layer-in-detail"></a>Configuration layer in detail</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Layers are passed to Glue using JVM parameter</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">java -Dglue.layers=/testdata/layer1,/testdata/layer2</code></pre>
</div>
</div>
<div class="sect2">
<h3 id="trueoverride-property-value"><a class="anchor" href="#trueoverride-property-value"></a>Override Property Value</h3>
<div class="paragraph">
<p>If we have two properties files at same location under different layers. Glue will try to
override or merge property file in same order as configuration layers are defined.
For example:</p>
</div>
<div class="listingblock">
<div class="title">Layer 1 (/testdata/layer1/)</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/MergedComponent
$class=in.erail.glue.component.PropertiesComponent
$scope=LOCAL
propString=TestString
propArray=a,b,\
    c
propList=a,b,\
    c
propMap=a=b,c=d,\
    e=f
propComponent=/in/erail/glue/test/component/PropertiesComponent
propJson=testconfig.json
propSet=a,b,b,c</code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">Layer 2 (/testdata/layer2/)</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/MergedComponent
propString=TestString2
propArray=a
propList-=a
propList+=b,c,d
propMap-=a=b
propMap+=z=b
propComponent=/in/erail/glue/test/component/PropertiesComponent2
propSet-=a,b
propSet+=e,f</code></pre>
</div>
</div>
<div class="sect3">
<h4 id="trueoverride-property-value-2"><a class="anchor" href="#trueoverride-property-value-2"></a>Override Property Value</h4>
<div class="paragraph">
<p>In above example, when instance of  <code>/in/erail/glue/test/component/MergedComponent</code>
is created,<code>PropertiesComponent.getPropString()</code> method will return <code>TestString2</code> instead
of <code>TestString</code>. As you can see in above example, <strong>Layer 2</strong> is overriding propString value.</p>
</div>
</div>
<div class="sect3">
<h4 id="truemerge-property-value"><a class="anchor" href="#truemerge-property-value"></a>Merge Property Value</h4>
<div class="paragraph">
<p>In case of List,Map,Set. Glue supports merge or deletion of property value. In above
example, <code>PropertiesComponent.getPropList()</code> will return list with elements b,c,b,c,d.
<code>Hyphen(-)</code> in <code>propList-=a</code> will remove <strong>a</strong> from list. And <code>Plus(+)</code> in <code>propList+=b,c,d</code> will
add <strong>b,c,d</strong> elements to list. Same can be done in case of Map and Set.</p>
</div>
</div>
<div class="sect3">
<h4 id="truecomponent-property"><a class="anchor" href="#truecomponent-property"></a>Component Property</h4>
<div class="paragraph">
<p>A component property can refer to another component property.As can be seen in
<code>/in/erail/glue/test/component/PropertiesComponent</code>,</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">propComponent=/in/erail/glue/test/component/GlobalObjectByDefault</code></pre>
</div>
</div>
<div class="paragraph">
<p><code>PropertiesComponent.getPropComponent()</code> will return instance of <strong>GlobalObjectByDefault</strong>
component.</p>
</div>
</div>
<div class="sect3">
<h4 id="truecomponent-property-referring-to-another-component-property"><a class="anchor" href="#truecomponent-property-referring-to-another-component-property"></a>Component property referring to another component property</h4>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/component/RefPropertiesComponent
$class=in.erail.glue.component.PropertiesComponent
$scope=LOCAL
propString^=/in/erail/glue/test/component/PropertiesComponent.propString
propArray^=/in/erail/glue/test/component/PropertiesComponent.propArray
propList^=/in/erail/glue/test/component/PropertiesComponent.propList
propMap^=/in/erail/glue/test/component/PropertiesComponent.propMap
propComponent^=/in/erail/glue/test/component/PropertiesComponent.propComponent
propBoolean^=/in/erail/glue/test/component/PropertiesComponent.propBoolean
propEnum^=/in/erail/glue/test/component/PropertiesComponent.propEnum
propJson^=/in/erail/glue/test/component/MergedComponent.propJson
propServiceMap^=/in/erail/glue/test/component/PropertiesComponent.propServiceMap</code></pre>
</div>
</div>
<div class="paragraph">
<p>As can be seen above. <strong>^</strong> is used for connecting  component property to another
component property.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="truefactory-based-creation-of-component"><a class="anchor" href="#truefactory-based-creation-of-component"></a>Factory based creation of Component</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Glue supports two factory classes which you can use to create instance of classes requiring
factory for creation. For more example, refer to test cases.</p>
</div>
<div class="sect2">
<h3 id="truemethodinstancefactory"><a class="anchor" href="#truemethodinstancefactory"></a>MethodInstanceFactory</h3>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/factory/TestComponentPC2
$class=in.erail.glue.factory.TestComponent
$instanceFactory=/in/erail/glue/test/factory/MethodInstanceFactory
$factory.class=in.erail.glue.factory.TestFactory
$factory.method.name=create
$factory.param.values=ninja,5
#factory.param.type=
#factory.instance=
$scope=GLOBAL</code></pre>
</div>
</div>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Field Name</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">instanceFactory</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Reference to component: in.erail.glue.factory.MethodInstanceFactory</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">factory.class</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Class responsible for creating instance</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">factory.instance</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Path of component responsible for creation of instance</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">factory.method.name</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Method name</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">factory.param.values</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Method parameters (Support component path also)</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">factory.param.type</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Optional method parameter type</p></td>
</tr>
</tbody>
</table>
</div>
<div class="sect2">
<h3 id="trueparameterconstructorinstancefactory"><a class="anchor" href="#trueparameterconstructorinstancefactory"></a>ParameterConstructorInstanceFactory</h3>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">#/in/erail/glue/test/factory/TestComponentPC1
$class=in.erail.glue.factory.TestComponent2
$instanceFactory=/in/erail/glue/test/factory/ParameterConstructorInstanceFactory
$constructor.param.values=ninja,5,/in/erail/glue/test/component/PropertiesComponent,"a,b"
$scope=GLOBAL</code></pre>
</div>
</div>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Field Name</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">instanceFactory</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Reference to component: in.erail.glue.factory.MethodInstanceFactory</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">constructor.param.values</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Constructor parameters (Support component path also)</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">constructor.param.type</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Optional constructor parameter type</p></td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="trueadvance"><a class="anchor" href="#trueadvance"></a>Advance</h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="trueconfiguration-using-glue-config-file"><a class="anchor" href="#trueconfiguration-using-glue-config-file"></a>Configuration using glue.config file</h3>
<div class="paragraph">
<p>Glue picks any configuration from three places in given order:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>From Java command line (e.g. -Dglue.layer)</p>
</li>
<li>
<p>From Environment variable (e.g. GLUE_LAYER)</p>
</li>
<li>
<p>glue.config file</p>
</li>
</ol>
</div>
<div class="listingblock">
<div class="title">glue.config example</div>
<div class="content">
<pre class="highlightjs highlight"><code class="language-ini" data-lang="ini">glue.layers=/common</code></pre>
</div>
</div>
<div class="paragraph">
<p>To pass glue.config use <strong>-Dglue.config=/var/task/glue.config</strong></p>
</div>
</div>
<div class="sect2">
<h3 id="trueimprove-config-loading-performance"><a class="anchor" href="#trueimprove-config-loading-performance"></a>Improve config loading performance</h3>
<div class="paragraph">
<p>Normally, all properties files are loaded from layer location each time glue is started. To imporove performance, Glue can cache loaded configuration in file file. On any future restarted, Glue will first try to load full configuration from cache configuration file.
This setup can be used in production to save some load time.</p>
</div>
<div class="paragraph">
<p>By default, configuration is always loaded from layers. To activate caching of configuration, you will have to use a different configuration loader as shown below.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="highlightjs highlight"><code class="language-sh" data-lang="sh">-Dglue.serialization.factory=in.erail.glue.factory.LocalConfigSerializationFactory</code></pre>
</div>
</div>
<table class="tableblock frame-all grid-all spread">
<caption class="title">Table 1. LocalConfigSerializationFactory additional param which can pass in command line</caption>
<colgroup>
<col style="width: 33.3333%;">
<col style="width: 33.3333%;">
<col style="width: 33.3334%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">Environment Variable</th>
<th class="tableblock halign-left valign-top">Default</th>
<th class="tableblock halign-left valign-top">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">local.config.factory.file.location</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Current working directoy</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Directory from where file is loaded or saved</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">local.config.factory.file.name</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">glue.ser</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">Default file name</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">local.config.factory.identifier</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">.default</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">While generating file. Files can be generated with different identifier to generated different config files (for example for different env)</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">local.config.factory.disable.save</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">false</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">If enable, then each time Glue     starts, all layers are saved into file, which can be used in future to load configuration.</p></td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
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